1. HM / HH series DTH hammer valveless gas distribution using the latest principles of design, so that the impact is to get a good energy conversion, a single large impact energy, the impact of frequency, high speed, air consumption Bottom 2. HM / HH series DTH hammer made of high quality alloy materials and the most advanced processing, heat treatment process, more stable performance and longer life. 3. HM / HH series impactor simple structure, easy disassembly, easy maintenance, low failure rate.